Multi-element prescription lenses with eye-tracking

ABSTRACT

The disclosed embodiments are generally directed to optical systems. The optical systems may include a proximal lens that may transmit light toward an eye of a user. The optical systems may also include a distal lens that may, in combination with the proximal lens, correct for at least a portion of a refractive error of the eye of the user. The optical systems may further include a selective transmission interface. The selective transmission interface may couple the proximal lens to the distal lens, transmits light having a selected property, and does not transmit light that does not have the selected property. The optical system can also include an accommodative lens, such as a liquid lens. Various other methods, systems, and computer-readable media are also disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.17/102,698, filed on 24 Nov. 2020, which is a Continuation of U.S.application Ser. No. 16/041,634 filed on 20 Jul. 2018, which claims thebenefit of U.S. Provisional Application No. 62/646,900 filed on 22 Mar.2018 and U.S. Provisional Application No. 62/650,254 filed on 29 Mar.2018, the disclosures of each of which are incorporated, in theirentirety, by this reference.

BACKGROUND

Conventional optical lenses may exhibit chromatic aberration, which maybe characterized as the inability of the lenses to focus colors of agiven band to the same physically convergent point in space. Suchchromatic aberration, which may also be referred to as chromaticdistortion, may result from dispersion effects in the lenses caused bythe lenses having different refractive indices corresponding todifferent wavelengths of light. Because the focal length of a lens isdependent on the refractive index of the lens, different wavelengths oflight may be focused at different depths with respect to the lens, whichmay lead to visual artifacts such as color fringing and the like.

SUMMARY

As will be described in greater detail below, the instant disclosuredescribes corrective optical media that may include embedded selectivetransmission interfaces and/or eye tracking in optical devices such asvirtual reality (VR), augmented reality (AR), and/or mixed-realitysystems.

In various embodiments, an optical system is presented. The opticalsystem may include a proximal lens configured to transmit light towardan eye of a user. The optical system may also include a distal lensconfigured to, in combination with the proximal lens, correct for atleast a portion of a refractive error of the eye of the user. Theoptical system may further include a selective transmission interfacethat couples the proximal lens to the distal lens, transmits lighthaving a selected property, and does not transmit light that does nothave the selected property.

In an example, the selected property may include a passband range ofwavelengths, the selective transmission interface may transmit lightwithin the passband range, and the selective transmission interface maybe at least partially non-transmissive outside the passband range. In anexample, the optical system may further include a sensor, and thepassband range may include at least a portion of a visible spectrum oflight. The selective transmission interface may be configured to reflectat least a portion of an infrared spectrum of light such that infraredlight reflected from the eye of the user may be diverted toward thesensor. In an example, the selected property may include a polarizationstate of electromagnetic radiation and the selective transmissioninterface may include a reflective polarizer configured to transmitlight having a first polarization state and to reflect or absorb lighthaving a second polarization state that may be different than the firstpolarization state.

In an example, the optical system may further include an eye-trackingsubsystem programmed to use an output of the sensor to track movement ofthe eye of the user. The eye-tracking subsystem may be programmed totrack a gaze direction of both a right eye of the user and a left eye ofthe user. The eye-tracking subsystem may also be programmed tocalculate, based on the gaze directions of the right and left eyes ofthe user, a depth at which the right and left eyes of the user arefocused. In such examples, the distal lens may include an accommodativelens and the eye-tracking subsystem may be programmed to trigger achange in an optical power of the accommodative lens based on the depthat which the right and left eyes are focused.

In an example, at least one of the distal lens and the proximal lens mayinclude a liquid lens, and the selective transmission interface mayinclude a backplane of the liquid lens. In some embodiments, theselective transmission interface may include a hot-mirror coating.Additionally or alternatively, the selective transmission interface mayinclude an optical substrate having a plurality of concentric facets. Incertain examples, the proximal and distal lenses may be configured as adoublet lens that reduces at least one of a chromatic aberration causedby the proximal lens and a chromatic aberration caused by the distallens.

In an example, the optical system may further include an eyewear framedimensioned to secure the proximal lens, the distal lens, and theselective transmission interface in front of the eye of the user. Theoptical system may also include a head-worn display configured totransmit images through the distal lens, the selective transmissioninterface, and the proximal lens to the eye of the user.

In various embodiments, a method may include receiving, from an opticalsensor, information about light reflected off an eye of a user. Thelight may be directed to the optical sensor by a doublet lens having (i)a proximal lens configured to transmit light toward an eye of a user,(ii) a distal lens configured to, in combination with the proximal lens,correct for at least a portion of a refractive error of the eye of theuser, and (iii) a selective transmission interface. The selectivetransmission interface may couple the proximal lens to the distal lens,may transmit light within a passband range of wavelengths, and may be atleast partially non-transmissive outside the passband range.

The method may further include detecting, based on the information aboutthe light reflected off the eye of the user, a gaze of the user. Themethod may also include, in response to detecting the gaze of the user,changing a state of an optical system (e.g., a system that includes theoptical sensor and the doublet lens) worn by the user.

In an example, changing the state of the optical system may include atleast one of modifying a focal length of a display and changing a focusof an accommodative lens. Furthermore, detecting the gaze of the usermay include (i) tracking a gaze direction of both a right eye of theuser and a left eye of the user and (ii) calculating, based on the gazedirections of the right and left eyes of the user, a depth at which theright and left eyes of the user are focused. In an example, at least oneof the proximal and distal lenses may be an adjustable lens and changingthe state of the optical system may include triggering an actuator tomodify an optical property of the adjustable lens by deforming theadjustable lens.

Various embodiments may involve a method for manufacturing or assemblingan optical system. The method may include coating an optical substratewith a selective transmission layer that transmits light within apassband range of wavelengths and may be at least partiallynon-transmissive outside the passband range. The method may also includecoupling a proximal surface of the optical substrate to a proximal lensconfigured to transmit light toward an eye of a user. The method mayfurther include coupling a distal surface of the optical substrate to adistal lens configured to, in combination with the proximal lens,correct for at least a portion of a refractive error of the eye of theuser. In an example, the method may additionally include securing theoptical substrate, the proximal lens, and the distal lens to a head-wornoptical system.

In various embodiments, an optical system may include a structuralsupport element that transmits light having a selected property and doesnot transmit light that does not have the selected property. The opticalsystem may further include an adjustable lens coupled to the structuralsupport element. The adjustable lens may include a deformable elementthat (i) may be supported by the structural support element such thatthe structural support element includes a backplane of the adjustablelens and (ii) when deformed, changes an optical property of theadjustable lens. In an example, the optical system may include aheadwear frame configured to hold the structural support element suchthat a proximal surface of the structural support element faces a userand a distal surface of the structural support element includes thebackplane of the adjustable lens.

In an example, the selected property may include a passband range ofwavelengths such that the structural support element may transmit lightwithin the passband range of wavelengths and may be at least partiallynon-transmissive for light outside the passband range. Furthermore, theoptical system may include a sensor. In such embodiments, the passbandrange may include at least a portion of a visible spectrum of light andthe structural support element may be configured to reflect at least aportion of an infrared spectrum of light such that infrared lightreflected from an eye of a user may be diverted toward the sensor.

In an example, the adjustable lens may be configured to correct for atleast a portion of a refractive error of an eye of the user. The opticalsystem may also include an adjustable lens including a liquid lens andthe deformable element may be sealed to the structural support elementto hold a deformable optical medium within a cavity located between thedeformable element and the structural support element. In suchembodiments, the structural support element may include a non-zerooptical power.

In an example, the optical system may include an eye-tracking subsystemprogrammed to use an output of the sensor to track movement of the eyeof the user. The eye-tracking subsystem may be programmed to track agaze direction of both a right eye of the user and a left eye of theuser and calculate, based on the gaze directions of the right and lefteyes of the user, a depth at which the right and left eyes of the userare focused. In an example, the adjustable lens may include anaccommodative lens and the eye-tracking subsystem may be programmed totrigger a change in an optical property of the adjustable lens based onthe depth at which the right and left eyes are focused.

In an example, the selected property may include a polarization state ofelectromagnetic radiation and the structural support element may includea reflective polarizer configured to transmit light having a firstpolarization state and to reflect light having a second polarizationstate that may be different from the first polarization state. In anexample, the adjustable lens may include a liquid lens and thestructural support element may include a backplane of the liquid lens.In some embodiments, the structural support element may include animmersed reflective surface. Additionally or alternatively, thestructural support element may include an optical substrate having aplurality of concentric facets. In certain examples, the structuralsupport element and the adjustable lens may be configured in a mannerthat reduces a chromatic aberration caused by the adjustable lens. In anexample, the optical system may include a head-worn display configuredto transmit images through both the structural support element and theadjustable lens to an eye of a user.

In various embodiments, an optical system is disclosed. The opticalsystem may include a rigid lens having a non-zero optical power. Theoptical system may also include an adjustable lens coupled to the rigidlens, and the adjustable lens may include a deformable element that (1)may be supported by the rigid lens such that the rigid lens includes abackplane of the adjustable lens and (2) when deformed, may change anoptical property of the adjustable lens. In an example, the opticalsystem may include an actuator that, when actuated, applies a force tothe adjustable lens that causes the adjustable lens to deform in amanner that changes the optical property. In an example, the opticalsystem may include a head-worn frame dimensioned to hold the rigid lensand the adjustable lens in front of an eye of a user, and the adjustablelens may be configured to correct for at least a portion of a refractiveerror of the eye of the user.

In various embodiments, a method may include receiving, from an opticalsensor, information about infrared light reflected off an eye of a user,and the infrared light reflected off the eye of the user may be directedto the optical sensor by an optical element. The optical element mayinclude a structural support element that: transmits at least a portionof light in a visible spectrum and reflects at least a portion of lightin an infrared spectrum. The optical element may further include anadjustable lens coupled to the structural support element. Theadjustable lens may include a deformable element that is supported bythe structural support element such that the structural support element(i) forms a backplane of the adjustable lens and when deformed, (ii)changes an optical property of the adjustable lens. The method mayfurther include detecting, based on the information about the lightreflected off the eye of the user, a gaze of the user, and in responseto detecting the gaze of the user, changing a state of an optical systemthat includes the optical sensor and the optical element.

Features from any of the above-mentioned embodiments may be used incombination with one another in accordance with the general principlesdescribed herein. These and other embodiments, features, and advantageswill be more fully understood upon reading the following detaileddescription in conjunction with the accompanying drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate a number of exemplary embodimentsand are a part of the specification. Together with the followingdescription, these drawings demonstrate and explain various principlesof the instant disclosure.

FIG. 1 shows an example optical layout of a doublet lens and aneye-tracking system in accordance with example embodiments of thedisclosure.

FIG. 2 shows an example optical layout of a doublet lens including aselective transmission interface in an eye-tracking system in accordancewith example embodiments of the disclosure.

FIG. 3 shows an example simulated ray-tracing diagram with angles ofchief rays and reference rays corresponding to points on the eye thatare captured by a sensor of the eye tracking system in accordance withexample embodiments of the disclosure.

FIG. 4 shows an example simulated ray-tracing diagram with angles ofchief rays and reference rays corresponding to points on the eye thatare captured by a sensor of the eye tracking system, in accordance withexample embodiments of the disclosure.

FIG. 5A shows a doublet lens having a selective transmission interface,where the optical media is different for both elements of the doubletlens.

FIG. 5B shows a diagram of light being deviated by the action of theselective transmission interface as it passes through the doublet lens.

FIG. 5C shows a triplet lens having a selective transmission interfaceas a middle element of the triplet lens, and where the optical media arethe same on either side of the Fresnel surface.

FIG. 5D shows a diagram of light being less deviated by the action ofthe selective transmission interface as it passes through the tripletlens, in comparison with the doublet lens.

FIG. 6A shows an example diagram of Fresnel reflections from a firstsurface of a lens, where the first surface of the lens has no curvature,in accordance with example embodiments of the disclosure.

FIG. 6B shows an example diagram of Fresnel reflections from a firstsurface of a lens, where the first surface of the lens has curvature(e.g., the lens is concave), in accordance with example embodiments ofthe disclosure.

FIG. 7 shows example doublet lens and triplet lens designs, inaccordance with example embodiments of the disclosure.

FIGS. 8A and 8B shows a diagram of example master molds that may be usedin a molding process for the fabrication of a doublet lens, inaccordance with example embodiments of the disclosure.

FIG. 9 shows an example optical layout of a lens, eye-trackingcomponent, and an unactuated, accommodative (e.g., liquid) lens, inaccordance with example embodiments of the disclosure.

FIGS. 10A and 10B show another example optical layout of an eye,eye-tracking component, and an actuatable, accommodative lens, inaccordance with example embodiments of the disclosure.

FIGS. 11A and 11B show another example optical layout of an eye,eye-tracking component, and actuatable, accommodative lens including acurved optical substrate, in accordance with example embodiments of thedisclosure.

FIG. 12A shows a plot of the amount of magnification versus the opticalpower of an accommodative lens, where the optical power is variedbetween −3 diopters (D) to +3 D, in accordance with example embodimentsof the disclosure.

FIG. 12B shows a plot of the amount of magnification versus the opticalpower of an accommodative lens, where the optical power is variedbetween 20 D to 40 D, in accordance with example embodiments of thedisclosure.

FIG. 13 shows an example flow-diagram for performing example operationsof the optical systems and components various described herein, inaccordance with example embodiments of the disclosure.

FIG. 14 shows another example flow-diagram for performing exampleoperations of the optical systems and components various describedherein, in accordance with example embodiments of the disclosure.

Throughout the drawings, identical reference characters and descriptionsindicate similar, but not necessarily identical, elements. While theexemplary embodiments described herein are susceptible to variousmodifications and alternative forms, specific embodiments have beenshown by way of example in the drawings and will be described in detailherein. However, the exemplary embodiments described herein are notintended to be limited to the particular forms disclosed. Rather, theinstant disclosure covers all modifications, equivalents, andalternatives falling within the scope of the appended claims.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The present disclosure is generally directed to various types of lenses,such as lenses that may be used in eyewear (e.g., spectacles) or inelectronic devices such as virtual reality (VR) systems, augmentedreality (AR) systems, and mixed reality (MR) systems. In particular,some embodiments are directed to corrective lenses that may be worn infront of the eye to improve vision. Corrective lenses may be used totreat refractive errors of the eye, which may include, for example,myopia, hypermetropia, astigmatism, presbyopia, and the like.Prescription lenses may be customized to correct for a given user'srefractive errors, which may include various components, such as asphere component to address myopia and/or presbyopia, a cylindercomponent to address astigmatism, and a prism component to addressstrabismus and other binocular vision disorders.

To correct for such refractive errors, singlet lenses may be used;however, singlet lenses may introduce chromatic aberrations, which mayvary based on the Abbe number of the optical media composing the singletlenses. The Abbe number, also known as the V-number or constringence,may generally refer to a measure of a material's dispersion (i.e.,variation of refractive index versus wavelength), with high values of Vindicating low dispersion. Further, lower-order chromatic aberration mayinclude axial or transverse types, and the human eye may be particularlysensitive to transverse chromatic aberrations (TCA). Corrective lenses,such as achromatic doublet lenses, may correct for chromatic aberrationssuch as TCA. However, the cost, weight, and form-factor of such doubletlenses may make them impractical for use as corrective lenses in varioussituations.

In addition to being used in traditional eyeglasses, corrective lensesmay be used to correct for users' refractive errors in augmented reality(AR) glasses and/or virtual reality (VR) headsets. The refractive indexof common optical media used in ophthalmic lenses may range fromapproximately 1.49 to approximately 1.76. However, to reduce the weightand volume of corrective lenses used in AR glasses, lenses having higherrefractive index materials may need to be used. However, such higherrefractive index materials may be characterized by lower Abbe numberswhich may correspond to higher dispersions and may therefore lead tolenses that have greater chromatic aberrations.

As will be explained in greater detail below, embodiments of the instantdisclosure may provide an optical system for prescription-based visioncorrection. In one embodiment, the optical system may include at leasttwo lenses coupled together at a selective transmission interface andthe bonded lenses may form a doublet lens. In another example, theselective transmission interface may include optical coatings orpatterns such that the selective transmission interface transmitsradiation having a given property (e.g., a given wavelength range) butabsorbs or reflects radiation having another, different property (e.g.,a different wavelength range).

In some embodiments, a camera or a sensor (e.g., a photodetector) may belocated in a predetermined position with respect to the lens (e.g., thedoublet lens having corrective properties). In one example, at least aportion of radiation incident on the selective transmission interfacemay be directed towards the camera or the sensor by the selectivetransmission interface.

In additional embodiments, an optical system may include an opticalsubstrate that preferentially reflects radiation of a first type (e.g.,infrared radiation) and preferentially transmits or absorbs radiation ofa second type (e.g., visible light). In some examples, the opticalsubstrate may physically support an accommodation lens, such as a liquidlens.

In some embodiments, the optical systems described herein may beincluded in an augmented reality or virtual reality device that hascorrective lenses, an eye-tracking module, and accommodative lenses.Additionally or alternatively, a monolithic optical component may serveas a corrective lens, such as prescription lens, and as an eye-trackingdevice at the same time. Providing two or more components as monolithicdevices can lead to reduced bulk and size.

Various embodiments of the disclosure may have many applications,including applications in displays (e.g., in AR and/or VR displays), incorrective lenses (e.g., prescription lenses), in surgical instruments,and the like. In display applications, eye-tracking may provideinformation about the gaze of the eyes which may be used to determinethe depth of the plane at which the eyes are focused, which can be usedto determine an accommodative state of the eyes. Eye tracking may behelpful in display system applications having a fixed focus, where thephenomenon of vergence-accommodation conflict may be a source ofdiscomfort for the user. Vergence-accommodation conflict vergence mayrefer to the difficulty in adjusting the vision of the eyes during thesimultaneous movement of both eyes in opposite directions to obtain ormaintain single binocular vision. In some examples, the disclosedoptical systems may enable the use of a liquid lens that may modulatethe curvature of the wave front of the light emitted by the display intothe user's eyes and thereby reduce the effects of vergence-accommodationconflict.

In some further examples related to display applications (e.g., ARdisplays), the displays may present images that may be visuallyperceived at optical infinity. To visualize such images, an eye of theuser may not need to accommodate (that is, change optical power tomaintain focus) on such images. In some examples, depending on thecontent being projected in such images, some objects might need to beportrayed at different depths than others. Moreover, content might needto be projected at a depth that is fixed with respect to the outsideworld and/or the user's eyes. To ensure that objects are rendered atoptimal depth, a closed-loop system including an eye-tracker and anaccommodative lens (e.g., a liquid lens or a liquid crystal lens) asdescribed variously herein may be needed. In another example, to ensurethat the real world remains in focus in the AR display, additionalaccommodative lenses (e.g., additional liquid lenses or liquid crystallenses) of equal and opposite optical power to the first accommodativelens may be needed.

In vision correction applications, some users' eyes may not have theability to optimally accommodate their vision. For example, as usersage, the crystalline lenses in the users' eyes may become stiffer andmore resistant to changes in morphology, leading to a visual conditionknown as presbyopia, where nearby objects may become difficult to focuson; thus, accommodation may be needed to visualize nearby objects. Insome examples, with eye-tracking and accommodative (e.g., liquid)lenses, a closed-loop system may be implemented that may determine theuser's gaze, estimate the depth of a given object that a user is tryingto focus on, and change the shape of the accommodative lens accordinglyto bring the object into focus. Further, as described, one or moreaccommodative lenses may be installed in a given optical system, inaccordance with example embodiments of the disclosure. For AR displays,the display system may be placed between at least two accommodativelenses so that the optical effects of one accommodative lens may bereversed by the other accommodative lens.

In surgical applications, magnifying lenses having zooming ability canbe useful. In an embodiment, one or more accommodative (e.g., liquid)lenses may function relatively synchronously, for example, to provide apositive optical power as compared with a passive, positive focal-lengthlens. The cumulative positive optical power may, in such an embodiment,be equal to the sum of the optical powers provided by each accommodativelens. Such an optical system may serve as a lens having zoomingproperties (i.e., a lens that allows for controlled opticalmagnification). In some examples, such a lens having zooming propertiesmay be worn by the user. Further, in combination with a determination ofthe user's gaze through eye-tracking, the optical system may use suchaccommodative lens assemblies to zoom in and magnify objects of interestthat are within the field-of-view of the user. Moreover, practitionersin the medical field (e.g., dentists, surgeons, etc.) may wear loupesfor magnifying images of biological tissue during procedures. Suchloupes may, for example, have a two to five-fold magnificationpotential. The accommodative (e.g., liquid) lens assemblies describedherein may be used in the manufacture of such loupes. In addition tosurgical applications, such accommodative lens assemblies may be used bymany diverse applications, such as jewelry fabrication and repair,readers of fine print text, small-scale electronics work, etc.

The following will provide, with reference to FIGS. 1-14 , detaileddescriptions of systems, methods, and apparatuses for optical systemsthat include corrective lenses having embedded selective transmissioninterfaces and having accommodative lenses. The discussion associatedwith FIGS. 1-4 includes descriptions of doublet lens configurations. Thediscussion relating to the embodiment depicted in FIGS. 5 and 6 show thedeviation of light and associated Fresnel reflections cause by thelenses described herein. The discussion associated with FIG. 7 includesdescriptions of example doublet lens and triplet lens designs. FIG. 8and related discussion describe fabrication methods for the lenses. Thediscussion associated with FIGS. 9-11 describes example optical layoutsof a static lens, an eye-tracking component, and an accommodative (e.g.,liquid) lens that may be used with various embodiments. The discussionof FIG. 12 describes the graphs of the optical power of example lensesversus the magnification provided by the lenses that can be used invarious embodiments herein. The discussions of the methods depicted inFIGS. 13-14 are presented in the context of FIGS. 9-11 to describe howsome embodiments provide for prescriptive vision correction in additionto eye-tracking. While many of the examples discussed herein may bedirected to head-worn display systems, embodiments of the instantdisclosure may be implemented in a variety of different types of devicesand systems.

As noted, the present disclosure is directed to multi-element lenses,such as doublet lens 104, as shown in diagram 100 of FIG. 1 . Thedoublet lens 104 may be configured with a variety of lenses or otheroptical elements. For example, the doublet lens 104 may include aproximal lens 140 configured to transmit light toward an eye 101 of auser (e.g., toward a pupil 102 of the eye 101). The doublet lens 104 mayalso include a distal lens 150 configured to, in combination with theproximal lens 140, correct for at least a portion of a refractive errorof the eye 101 of the user.

The proximal lens 140 may include any suitable form of lens that isconfigured to be used in any suitable manner. In some embodiments, aproximal lens, such as proximal lens 140, may be a lens with at leastone surface facing toward a user. For example, an outside surface of theproximal lens 140 may be configured to transmit light any suitabledistance (e.g., between 10 mm and 20 mm) to the eye 101 of the user.Furthermore, proximal lens 140 may be configured as any suitable typesof lens (e.g., a concave lens, convex lens, etc.).

As with the proximal lens 140, the distal lens 150 may be configured asany suitable type of lens that is configured to be used in any suitablemanner. In some embodiments, a distal lens, such as distal lens 150, maybe a lens with at least one surface facing away from an eye 101 of theuser. The distal lens 150 may also include a second surface 120 that maybe curved to have additional optical power, which may be used to providea prescriptive correction for the eye 101 of the user. Furthermore, thedistal lens 150 may be configured as any suitable type of lens (e.g., aconcave lens, a convex lens, etc.).

As noted, the distal lens 150 may be configured to, in combination withthe proximal lens 140, correct for at least a portion of a refractiveerror of the eye 101 of the user. For example, the shape and/orcurvature of the distal lens 150 in combination with the proximal lens140 may provide a correction to the user's vision. Further, the distallens 150 may be configured to, in combination with the proximal lens140, correct for a refractive error associated with the distal lens. Therefractive error may include at least one of a chromatic aberrationcaused by the proximal lens 140 and a chromatic aberration caused by thedistal lens 150.

In some examples, the proximal lens 140 and/or the distal lens 150 mayinclude any suitable materials, such as glass and/or plastic. Theproximal lens 140 and/or the distal lens 150 may include a crown glassmaterial, such as a borosilicate crown glass material. In anotherembodiment, the crown glass may include additives such as zinc oxide,phosphorus pentoxide, barium oxide, and/or fluorite and lanthanum oxide,which may alter the optical or mechanical properties of the lenses. Inanother example, the proximal lens 140 and/or the distal lens 150 mayinclude a plastic material. For example, the proximal lens 140 and/orthe distal lens 150 may include a CR-39 lens material, due to its lowspecific gravity and low dispersion. In another example, the proximallens 140 and/or the distal lens 150 may include a polymer, such as aurethane-based polymer. In one embodiment, the lens may include aUV-blocking material, such as polycarbonate. Furthermore, the lens mayinclude a high-refractive-index plastic, such as thiourethanes, in whichsulfur content in the polymer may tune the index-of-refraction of theplastic.

In some examples, the proximal lens 140 and the distal lens 150 may beconnected to one another using any suitable material (e.g., anindex-matching material). In some embodiments, an index-matchingmaterial may refer to a substance, such as a liquid, cement (adhesive),or gel that has an index of refraction that closely approximates that ofanother object (e.g., a lens). By using an index-matching materialbetween two lenses of a doublet lens, radiation may pass from one lensto the other lens without significant reflection or refraction. In someexamples, polymers dissolved in volatile organic compounds (VOCs), suchas nitrocellulose and acrylic compounds dissolved in lacquer thinnerand/or a mixture of several solvents (typically containing butyl acetateand xylene or toluene), may be used as an index-matching layer.

The doublet lens 104 may further include a selective transmissioninterface 130 that couples the proximal lens 140 to the distal lens 150.In some embodiments, a common surface of the doublet lens 104 may serveas the selective transmission interface 130. In some examples, radiationfrom the eye 101 may pass through the proximal lens 140 at least twice,once on the way in and once on the way out of the proximal lens 140after a portion of the radiation is reflected by the selectivetransmission interface 130, with both portions of the radiation passingthrough the first surface 110.

The selective transmission interface 130 may be configured to transmitlight having a selected property and to not transmit light not havingthe selected property. In some examples, the selected property mayinclude a passband range of wavelengths. The selective transmissioninterface 130 may transmit light within the passband range, and theselective transmission interface 130 may be at least partiallynon-transmissive outside the passband range. In another example, thepassband range may include at least a portion of a visible spectrum oflight. In some embodiments, the selective transmission interface 130 mayreflect IR light outside the passable range. Additionally oralternatively, the selected property may include a polarization state ofelectromagnetic radiation and the selective transmission interface 130may include a reflective polarizer configured to transmit light having afirst polarization state and to reflect or absorb light having a secondpolarization state that is different than the first polarization state.

The selective transmission interface 130 may include a variety ofcompositions and configurations. In one embodiment, the selectivetransmission interface 130 may include a hot mirror coating, which mayreflect near-infrared radiation and may transmit and/or absorb visiblelight. In another embodiment, the selective transmission interface 130may include a dichroic filter that may reflect near-infrared radiationand may transmit and/or absorb visible light. In some embodiments, theselective transmission interface 130 may include an optical substratehaving a plurality of concentric facets. In a further embodiment, theselective transmission interface 130 may include a dielectric mirror(e.g., a Bragg mirror) that may reflect near-infrared radiation and maytransmit and/or absorb visible light. In another embodiment, thedielectric mirror may include a chirped mirror. A chirped mirror mayrefer to a dielectric mirror with chirped spaces (i.e., spaces ofvarying depth designed to reflect varying wavelengths of lights) betweenthe dielectric layers included in the mirror. FIG. 2 and the relateddiscussion provide a further description of such embodiments. Theselective transmission interface 130 may include a holographic film or adiffractive film. In some aspects, a holographic film may refer to athin film that is flexible plastic film [Polyester (PET), OrientedPolypropylene (OPP) and Nylon (Bonyl)] and which has been imprinted(e.g., micro-embossed) with patterns or images. In another aspect, adiffractive film may refer to a film that diffracts light to differentdirections based on the angle of incidence, wavelength, and otherfeatures of the light.

As mentioned, the doublet lens 104 may have any suitable configuration,which may vary, for example, depending on application. In some examples,the proximal lens 140, the distal lens 150, and the selectivetransmission interface 130 may be secured to an eyewear frame (notshown), dimensioned and positioned to be in front of the eye 101 of theuser. In some AR systems, the lens may be placed in front of thedisplay. Such displays may exhibit chromatic aberrations that arevisible to the human eye. Depending on the type of display and themagnitude of the aberrations, the doublet lens may be designed tocompensate for the display's chromatic aberrations.

In some configurations, reflected radiation from the eye 101 (e.g.,near-infrared radiation) may be diverted toward a camera orphotodetector (to be shown and described in connection with FIG. 3 ).

FIG. 2 shows another example optical system of a doublet lens includinga selective transmission interface in an eye-tracking system, inaccordance with example embodiments of the disclosure. In someembodiments, FIG. 2 may include similar components to the componentsshown and described in connection with FIG. 1 . In addition, FIG. 2shows an interface 230, which may be a diffraction grating such as aFresnel surface or an immersed Fresnel surface. In some embodiments, theinterface 230 may include an optical component with a periodic structurethat splits and diffracts radiation into several beams travelling indifferent directions. The directions of these beams may depend on thespacing and structure of the interface 230 as well as the wavelengths ofthe radiation such that the interface 230 serves as a dispersiveelement.

The interface 230 may be configured in any suitable configuration. Inone aspect, the interface 230 may be of a reflective or transmissivetype, analogous to a mirror or lens, respectively. In one embodiment,the interface 230 may have a zero-order mode, in which there is littleto no diffraction; accordingly, a ray of light interacting withinterface 230 may behave according to the laws of reflection andrefraction the same as with a mirror or lens, respectively. Such azero-order mode may be used to allow for light of a given wavelengthrange (e.g., visible light) to pass through the doublet lens 204 withoutperturbation. Higher order modes may also exist in the interface 230,and such higher order modes may be used to guide various components ofthe radiation to different areas. For example, the higher order modesmay be used to guide infrared wavelengths associated with infraredradiation towards a sensor (not shown).

In some embodiments, the interface 230 may be characterized by a blazingangle and a blazing wavelength. The blazing angle and the blazingwavelength may refer to the incident angle and wavelength for whichdiffraction is most efficient. Interface 230 may have a particulargroove density (e.g., a particular number of grooves per unit length,which may be expressed in grooves per millimeter (g/mm)) and equal tothe inverse of the groove period of the diffraction grating. In oneembodiment, the groove period of the interface 230 may be on the orderof the wavelength of interest (e.g., visible light or infrared light),as the spectral range covered by the interface 230 may be dependent onthe groove density. In some embodiments, the maximum wavelength that theinterface 230 may diffract may be equal to twice the grating period. Insome embodiments, the interface 230 may include a blazed grating, whichmay also be referred to as an Echelette grating. The interface 230 mayhave an optimized construction (e.g., groove periodicity) to achievemaximum a grating efficiency for a given direction corresponding to aparticular diffraction order of the interface 230 for a given portion ofthe incident spectrum. Accordingly, a maximum optical power may beconcentrated by the interface 230 in a desired direction analogous to aparticular diffraction order and corresponding, for example, to thelocation of a sensor. Moreover, the residual power in the other orders(e.g., orders that affect the visible portion of the spectrum) may besimultaneously minimized.

Interface 230 may include a variety of compositions and configurations.In one embodiment, interface 230 may include a hot mirror coating thatmay reflect near-infrared radiation and may transmit and/or absorbvisible light. In some embodiments, a hot mirror may be a dielectricmirror that may serve to protect optical components by reflectinginfrared light while allowing visible light to pass through. Hot mirrorsmay be inserted into the optical system shown in diagram 200 at anincidence angle varying between approximately zero and approximatelyforty-five degrees and may also prevent the buildup of waste heat thatmay damage components or adversely affect spectral characteristics ofany of the other components of the optical system.

In another embodiment, the selective transmission interface 230 mayinclude a dichroic filter that may reflect near-infrared radiation andmay transmit and/or absorb visible light. In particular, a dichroicfilter (e.g., a thin-film filter, an interference filter, etc.) may be afilter used to selectively pass light of a small range of wavelengthswhile reflecting other radiation having other wavelengths. Bycomparison, dichroic mirrors and dichroic reflectors may tend to becharacterized by the wavelength(s) of light that they reflect, ratherthan the wavelengths(s) they pass.

In some embodiments, a dichroic filter may include alternating layers ofoptical coatings with different refractive indices. The interfacesbetween the layers of different refractive indices may produce phasedreflections, selectively reinforcing certain wavelengths of radiationand interfering with other wavelengths. The layers may be deposited byvacuum deposition. By controlling the thickness and number of thelayers, the frequency (wavelength) of the passband of the filter may betuned and made as wide or narrow as desired.

In some embodiments, interface 230 may include an optical substratehaving a plurality of concentric facets. In a further embodiment,interface 230 may include a dielectric mirror (also known as a Braggmirror) that may reflect near-infrared radiation and transmit and/orabsorb visible light. In some embodiments, a dielectric mirror mayinclude a type of mirror composed of multiple thin layers of dielectricmaterial. By modifying the type and thickness of the dielectric layers,embodiments of this disclosure may provide an optical coating withspecified reflectivity at different wavelengths of radiation. In someembodiments, the dielectric mirror may include a stack of layers with ahigh refractive index interleaved with layers of a low refractive index.The thicknesses of the layers may be selected such that the path-lengthdifferences for reflections from different high-index layers are integermultiples of the wavelength for which the mirror is designed. In someembodiments, the dielectric mirrors may be fabricated using thin-filmdeposition methods, including, but not limited to, physical vapordeposition (e.g., evaporative deposition, ion beam assisted deposition,etc.), chemical vapor deposition, molecular beam epitaxy, sputterdeposition, and the like.

In another embodiment, interface 230 may include a chirped mirror. Achirped mirror may include a dielectric mirror with chirped spaces(e.g., spaces of varying depth designed to reflect varying wavelengthsof radiation) between the dielectric layers including the mirror. Insome embodiments, the chirped mirrors may be used to reflect a widerrange of wavelengths of radiation than ordinary dielectric mirrors ormay be used to compensate for the dispersion of wavelengths that may becreated by some optical elements, such as one or more portions of thedoublet lens 204.

In some embodiments, the chirped mirror may reflect radiation having arelatively wide range of frequencies. In some embodiments the chirpedmirror may have a first number (e.g., ten) of layers with a depthdesigned to reflect a certain wavelength of radiation, another number(e.g., ten) of layers with slightly greater depth to reflect a slightlylonger wavelength of radiation, and so on for the entire range ofwavelengths of radiation the mirror is designed to reflect. Accordingly,the chirped mirror may reflect a range of radiation wavelengths ratherthan single narrow band of wavelengths. This may be useful inapplications where a higher spectral range of wavelengths (e.g.,corresponding to a broader spectrum of infrared radiation) are reflectedby the chirped mirror to one or more sensors.

FIG. 3 shows an example simulated ray-tracing diagram with angles ofchief rays and reference rays corresponding to points on the eye thatare captured by a sensor (e.g., a camera) of the eye tracking system, inaccordance with example embodiments of the disclosure. In particular,the diagram 300 shows many of the same components that were shown anddescribed in connection with FIG. 1 .

As with diagram 100, diagram 300 shows the eye 101 positioned in frontof doublet lens 104. In this embodiment, the selective transmissioninterface 130 may be configured to reflect at least a portion of aninfrared spectrum of light such that infrared light 202 reflected fromthe eye 101 of the user is diverted toward a lens 305 that focuses theinfrared light 302 toward a sensor 310. As shown, diagram 300 depictssimulated ray-tracing illustrating angles of chief rays and referencerays of the infrared light 302 reflected from the eye 101 may correspondto points on the eye 101 that are captured by the sensor 310. Moreover,the components shown in FIG. 3 may be used in connection with ahead-worn display that may be configured to transmit images through thedistal lens 150, the selective transmission interface 130, and theproximal lens 140 to the eye 101 of the user.

In some examples, the radiation captured by the sensor 310 may bedigitized (i.e., converted to an electronic signal by the sensor 310).Further, a digital representation of this electronic signal may betransmitted to one or more processors (e.g., processors associated witha device such as an AR display).

In some embodiments, the sensor 310 may include any suitableconfiguration and/or may be any suitable type of sensor. For example,the sensor 310 may include an infrared detector that reacts to infraredradiation. The infrared detector may be a thermal detector, a photonicdetector, and/or any other suitable type of detector. Exemplary thermaldetectors may include detectors that react to thermal effects of theincident infrared radiation. For example, sensor 310 may be a bolometerthat may experience a change in resistance in response to infraredradiation. Additional examples that may be used as the sensor 310 mayinclude, but are not limited to, thermocouples and thermopiles, whichmay respond to a thermoelectric effect. Another example of sensor 310may include a Golay cell that detects incident infrared radiation basedon a thermal expansion effect.

As noted, the sensor 310 may include an optical sensor such as aphotonic detector, a photoconductive detector, a photovoltaic detector,and the like. In some embodiments, sensor 310 may be a photonic detectorthat includes a semiconductor with narrow band gaps. In anotherembodiment, sensor 310 may include a photoconductive detector thatchanges resistance when exposed to electromagnetic radiation. Suchphotoconductive detectors may use a p-n junction on which photoelectriccurrent appears upon illumination. In some embodiments, the sensor 310may include, but not be limited to, one or more of the followingdetector materials: mercury cadmium telluride (MCT), indium antimonide,indium arsenide, lead selenide, QWIP, QDIP, lithium tantalate (LiTaO₃),and/or triglycine sulfate (TGS).

In some examples, the digital representation generated by the sensor 310may be processed by the one or more processors to track the movement ofthe eye 101. In another example, the tracking of the movements of theeye 101 may be performed by executing, by the one or more processors,one or more algorithms represented by computer instructions stored onnon-transient memory. In some examples, at least a portion of suchalgorithms may be performed using on-chip logic (e.g., anapplication-specific integrated circuit (ASIC)).

In some embodiments, the eye-tracking subsystem may be programmed to usean output of the sensor 310 to track movement of the eye 101 of theuser. Furthermore, the digital representation generated by the sensor310 may be analyzed by the eye-tracking subsystem to track eye rotationby identifying changes in reflections. In one embodiment, cornealreflection (which may be referred to as a first Purkinje image) and/or acenter of the pupil 102 may be used as features to track over time. Inanother embodiment, a dual-Purkinje eye tracking process may beimplemented, which may use reflections from the front of the cornea(first Purkinje image) and the back of the lens (fourth Purkinje image)as features to track. In another embodiment, image features from insidethe eye 101, such as the retinal blood vessels, may be imaged andtracked as the eye rotates.

Purkinje images may be reflections of objects from the structure of theeye 101. They may also be referred to as Purkinje reflexes andPurkinje-Sanson images. The first Purkinje image may refer to thereflection from the outer surface of the cornea. The second Purkinjeimage may refer to the reflection from the inner surface of the cornea.The third Purkinje image may refer to the reflection from the outer(anterior) surface of the lens of the eye 101. The fourth Purkinje imagemay refer to the reflection from the inner (posterior) surface of thelens of the eye 101.

In some embodiments, the center of the pupil 102 and infrared ornear-infrared, non-collimated light may be used to create cornealreflections (CR). The vector between the pupil 102 center and thecorneal reflections may be used to compute the gaze direction of the eye101. In some embodiments a calibration procedure of the individual, suchas a calibration procedure to determine the vector mentioned above, maybe used to enable and/or improve the accuracy of eye-tracking techniquesdiscussed herein.

In some embodiments, two types of infrared and/or near-infrared (i.e.,active light) eye-tracking techniques may be used in accordance withthis disclosure: bright-pupil and dark-pupil eye-tracking, which may bedifferentiated based on the location of the illumination source (e.g.,the eye 101) with respect to the optics. If the illumination is coaxialwith the optical path, then the eye 101 may act as a retroreflector asthe light reflects off the retina, thereby creating a bright pupileffect similar to red eye. If the illumination source is offset from theoptical path, then the pupil 102 may appear dark because theretroreflection from the retina may be directed away from the sensor310. In some embodiments, bright-pupil tracking may create greateriris/pupil contrast, allowing more robust eye-tracking with irispigmentation and with reduced interference that may be caused byeyelashes and other obscuring features. It may also allow tracking inlighting conditions ranging from total darkness to very bright.

In another embodiment, the eye-tracking subsystem may be programmed totrack a gaze direction of both a right eye of the user and a left eye ofthe user. The eye-tracking subsystem may calculate, based on the gazedirections of the right and left eyes of the user, a depth at which theright and left eyes of the user are focused. In another example, thedetermination of the user's gaze and data related to the user's age(e.g., data receive as user input and/or as input from another system)may facilitate an estimation of an accommodative state for the eyes ofthe user. In some embodiments, the systems described herein may receivethe user's age via a user profile and/or other device setting. Forexample, an eye-tracking system may, for users at or above an age whenpresbyopia becomes more common, enable gaze-direction based correctionthat changes or implements correction depending on whether a user islooking down.

FIG. 4 shows an example simulated ray-tracing diagram with angles ofchief rays and reference rays corresponding to points on the eye thatare captured by a sensor of an eye tracking system, in accordance withexample embodiments of the disclosure. In particular, diagram 400 showsmany of the same components that were shown and described in connectionwith FIGS. 1-3 . The example simulated ray-tracing diagram 400 showsangles of chief rays and reference rays of the infrared light 402reflected from the eye 101 that may correspond to points on the eye 101that are captured by the sensor 310. Further, the light from the eye 101may reflect from a different surface in diagram 400 FIG. 4 versusdiagram 300 of FIG. 3 (e.g., surface of the proximal 140 or distal lens150 in FIG. 4 versus selective transmission interface 130 in FIG. 3 ).

FIG. 5A shows a doublet lens 501 having a selective transmissioninterface 504 where the optical media is different for the elements ofthe doublet lens, in accordance with example embodiments of thedisclosure. In another embodiment, doublet lens 501 may include a firstportion 502 and a second portion 506 and may also include lenses thatare made from optical media having different properties (e.g., differentindices of refraction). The doublet lens 501 may further include aselective transmission medium 504 (e.g., a diffractive grating such as aFresnel surface). The various components (e.g., the doublet lens 501 andthe selective transmission medium 504) may be similar, but notnecessarily identical to, corresponding components shown and describedabove in connection with FIGS. 1-4 .

FIG. 5B shows a diagram 503 of incident radiation 512 being refracted bythe action of the selective transmission interface (e.g., an immersedFresnel surface) 504 as it passes through the doublet lens 501, leadingto refracted light 516 having a deviated angle with respect to theincident radiation 512.

FIG. 5C shows a triplet lens 505 having a selective transmissioninterface 504 as a middle element of the triplet lens. In this example,the optical media for the optical elements on either side of theselective transmission medium 504 may be the same. In particular, thetriplet lens 505 may include a first portion 502 and a second portion508 on both sides of the selective transmission interface (e.g., adiffractive grating such as a Fresnel surface) 504. Further, the firstportion 502 and the second portion 508 may include optical media thatare composed of the same material and have similar optical propertiessuch as similar indices of refraction. The various components (e.g., thetriplet lens 505 and its various elements, the selective transmissionmedium 504, etc.) may be similar, but not necessarily identical to, thecomponents shown and described in connection with FIGS. 1-4 .

FIG. 5D shows a diagram of incident radiation 512 on the triplet lens505 being less refracted, relative to the embodiment of FIG. 5B, by theaction of the selective transmission interface 504 as it passes throughthe triplet lens 505. In particular, incident radiation 512 on thetriplet lens 505 may propagate through and exit the triplet lens 505 inan unperturbed fashion 518. Further, while the first portion 502 of thetriplet lens 505 and the second portion 508 of the triplet lens 505 mayhave the same index of refraction, a third portion 510 of the tripletlens 505 may have a different index of refraction in order to achieve aprescription-based visual correction for a user. In an embodiment, thecurvature of the outer surfaces of the first portion 502 and/or thethird portion 510 may be flat, aspherical, or any other suitable shapethat imparts a prescription-based effect on the vision of the user.

FIG. 6A shows an example diagram 600 of Fresnel reflections 611 from asurface of a doublet lens (e.g., a non-prescription doublet lens) 603having a selective transmission interface (not shown). In particular,the surface 604 of the doublet lens 603 may have no curvature and may beflat. In some embodiments, a radiation source (not shown) can be used togenerate radiation (e.g., infrared radiation), which may reflect off ofthe eye 601 to generate corneal reflections, which can be used ineye-tracking, as described above. The radiation source can include anysuitable device(s), for example, an infrared diode or an array ofinfrared diodes. In some aspects, the infrared diode or array ofinfrared diodes can be coupled to a the head-mounted display (e.g.,around the perimeter of a frame associated with the head-mounteddisplay). The infrared radiation that is reflected off of the eye 601may be diverted by the doublet lens 603 toward a sensor 610 and a sensorlens 605, as variously described herein. However, for some positions ofthe sensor 610 and/or the sensor lens 605, one or more visual artifacts,such as ghost images of the eye 601, may be generated due to Fresnelreflections by the selective transmission interface in combination withthe flat surface 604, and such ghost images may be captured by thesensor 610. These Fresnel reflections may be corrected by one or moreeye-tracking mechanisms (e.g., eye-tracking mechanisms based on trackingthe pupil 602) of an optical system based on such a doublet lensconfiguration. For example, an applied computer-vision algorithm can beused to correct for image ghosting effects.

FIG. 6B shows an example diagram of Fresnel reflections 621 from asurface 614 of a doublet lens (e.g., a prescription lens) 613 having aselective transmission interface (not shown). In particular, the surface614 of the doublet lens 613 may be concave. Further, the eye 601 mayreflect radiation (e.g., infrared radiation) that may be diverted by thedoublet lens 603 toward the sensor 610 and the sensor lens 605, asvariously described herein. In such a configuration (i.e., aconfiguration where the surface 614 of the doublet lens 613 is concave),a ray trace simulation of the configuration may show that Fresnelreflections 621 are less likely to be captured by the sensor 610. Inparticular, the rays representing the Fresnel reflections 621 thateventually make it to the sensor lens 605 may be incident at such steepangles that the rays may be less likely to introduce stray light ascompared to rays 603 of FIG. 6A. In other words, rays corresponding tothe Fresnel reflections 621 may be less likely to be Fresnel reflectedfrom the concave surface 614 of the doublet lens 603 and will not be asproblematic for detection by the sensor 610 in comparison with rays thatreflect from the flat surface 604 of FIG. 6A. This may be at leastpartly due to the fact that stray rays that would have been incident onthe sensor 610 may instead reflect off of the surface 614 and falloutside of the range of an aperture of the sensor 610. Further, in anoptical configuration with adequate baffling, such stray rays wouldlikely not fall on to the active area of the sensor 610. Accordingly,eye-tracking systems based on such an embodiment may benefit from areduction in ghost images and corrections resulting therefrom. Such areduction in ghost imaging may therefore represent an added advantage ofcombining the eye-tracking system with a prescription doublet-lens by,for example, increasing the efficiency and speed of one or moreeye-tracking systems and techniques.

FIG. 7 shows example doublet and triplet lens designs, where the varioussurfaces of the lens may be customized to have a particular opticalpower for correcting the vision of a given user. In someimplementations, a doublet lens such as doublet lens 701 may includedifferent designs to meet certain design specifications, including, butnot limited to, an angle of view, a maximum aperture, a resolution, adistortion, a color correction, a back focal distance, and the like. Insome embodiments, a doublet lens 701 is shown, which may include a firstportion of the doublet lens 702 and a second portion of the doublet lens704. In one embodiment, the first portion of the doublet lens 702 mayhave a surface 706 that may have a concave surface, as shown, or mayhave another shape (e.g., convex, flat, etc.). The first surface 706 mayhave a radius of curvature that may be designed to correct for a visualerror, such as myopia, presbyopia, and/or astigmatism. The secondportion of the doublet lens 704 may have a surface 708 that may be aconvex surface, as shown, or may have another shape. As with the surface706, the surface 708 may also have a radius of curvature that may bedesigned to correct for a visual error. The first portion of the doubletlens 702 and the second portion of the doublet lens 704 may havesurfaces 707 that are corrugated and may interlock when mechanicallycoupled to one another, for example, to serve as a selectivetransmission interface (e.g., a diffractive grating such as aFresnel-type reflector), as discussed above.

In some embodiments, a triplet lens 705 is shown, which may include afirst portion of the triplet lens 702, a second portion of the tripletlens 716, and a third portion of the triplet lens 716. In someimplementations, a triplet lens, such as triplet lens 705, may alsoinclude different designs to meet certain design specifications,including, but not limited to, an angle of view, a maximum aperture, aresolution, a distortion, a color correction, a back focal distance, andthe like.

In one embodiment, the first portion of the triplet lens 702 may have asurface 718 that may have a concave surface, as shown, or may haveanother shape (e.g., convex, flat, or freeform). The surface 718 mayhave a radius of curvature that may be designed to correct for a visualerror, such as myopia, presbyopia, and/or astigmatism. The secondportion of the triplet lens 716 may have a surface 714 that may be aflat surface not having any optical power, as shown, or may have anothershape (e.g., convex, or freeform). The first portion of the doublet lens702 and the second portion of the triplet lens 716 may have surfaces 707that are corrugated and may interlock when mechanically coupled to oneanother, for example, as a selective transmission interface (e.g., adiffractive grating such as Fresnel-type reflector of radiation, forexample, infrared radiation), as discussed herein. The third portion ofthe triplet lens 716 may have a surface 720 that may be a convexsurface, as shown, or may have another shape (e.g., concave, flat, orfreeform). The surface 720 may have a radius of curvature that may bedesigned to correct for a visual error, such as myopia, presbyopia,and/or astigmatism. In some embodiments, the triplet lens 705 mayfurther reduce the effects of chromatic aberration in comparison withthe doublet lens 701, discussed above.

FIG. 8A shows a diagram of master molds that may be used in a moldingprocess for the fabrication of a doublet lens, in accordance withexample embodiments of this disclosure. As mentioned, such a doubletlens may have a reduced chromatic aberration with respect to a singletlens. In particular, FIG. 8A shows a first diagram 801 for thefabrication of a first portion of a doublet lens 810 using a first mold802 and a second mold 806. In some examples, the first mold 802 may havea surface 804 that may be convex, as shown, or may have another shape(e.g., concave, flat, or freeform). This may allow for a surface 814 ofthe first portion of a doublet lens 810 to have a complementary shape(i.e., a concave shape) after fabrication. In some examples, the secondmold 806 may have a surface 808 that may be corrugated. This may allowfor a surface 814 of the first portion of a doublet lens 810 to have acorresponding corrugated shape after fabrication in order to, forexample, serve as a selective transmission medium such as a diffractiongrating. The second mold 806 may be designed to produce the firstportion of a doublet lens 810 having a given groove spacing,periodicity, blaze angle, etc.

In another embodiment, FIG. 8B shows a second diagram 803 for thefabrication of a second portion of a doublet lens 810 using a first mold812 and a second mold 816. In some examples, the first mold 812 may havea surface 814 that may be corrugated to, for example, serve as aselective transmission medium such as a diffraction grating (e.g., aFresnel-type surface). This may allow for a surface 822 of the secondportion of a doublet lens 820 to have a corrugated shape afterfabrication. In some examples, the second mold 816 may have a surface818 that may be convex, as shown, or may have another shape (e.g.,concave, flat, etc.). This may allow for a surface 824 of the secondportion of the doublet lens 820 to have a concave shape afterfabrication, which may also serve to provide a prescriptive correctionto a user's eye.

In another embodiment, after the fabrication of the first portion of thedoublet lens 810 and the second portion of the doublet lens 820 usingthe various molds described above, the first portion of the doublet lens810 and the second portion of the doublet lens 820 may be combined toform the doublet lens. The combining of the first portion of the doubletlens 810 and the second portion of the doublet lens 820 may be performedusing an index-matched optical material such as an optical adhesive, asfurther described in connection with FIG. 1 .

In some embodiments, one example fabrication process for fabricating thedoublet lenses may include injection molding or casting. In oneembodiment, master molds such as the first mold 802 and the second mold806, or the first mold 812 and second 816 may be generated by anysuitable process. Next the master molds may be used to fabricate thefirst portion of the doublet lens 810 and the second portion of thedoublet lens 820 (e.g., using injection molding or casting). After thefirst portion of the doublet lens 810 and the second portion of thedoublet lens 820 have been fabricated through molding, the corrugatedsurfaces (e.g., the Fresnel surfaces) such as surface 814 and surface822 on one of the first portion of the doublet lens 810 or the secondportion of the doublet lens 820 may be coated with an optical coating(e.g., using sputtering or vapor deposition or atomic layer depositiontechniques). In a further embodiment, the first portion of the doubletlens 810 and the second portion of the doublet lens 820 may be bondedtogether using index matching adhesives as described in connection withFIG. 1 . In an embodiment, a dip coating, such as a lacquer or ahard-coating, may be applied to the outer surfaces of the doublet lensto protect the doublet lens from scratches and to reduce the reflection,by the doublet lens, of unwanted stray light.

FIG. 9 shows an example optical system of a lens, eye-trackingcomponent, and an unactuated accommodative lens in accordance withexample embodiments of the disclosure. The optical system 900 mayinclude a variety of components and configurations. In particular, auser's eye 901 may be positioned behind a proximal lens 910 of a lensassembly 905 and may gaze through the lens assembly 905. Radiation(e.g., infrared light) may reflect off a selective transmissioninterface 920 and may be diverted toward a sensor. The radiation may beused to track the eye 901, for example, by tracking a pupil 902 of theeye 901 as described in connection with FIG. 2 .

Further, a distal lens 940 may be coupled to the selective transmissioninterface 920. The distal lens 940 may include an accommodative lensthat may be actuated by an actuator (not shown). Such an accommodativelens may change its shape and/or morphology in order to correct a user'svision. In another embodiment, an eye-tracking subsystem (not shown) maybe programmed to trigger a change in an optical power of the distal lens940 that serves as an accommodative lens based on the depth at which theright and left eyes are focused. In another embodiment, the distal lens940 may be unactuated in a first operational state, as shown, andtherefore, may not modify the view of an object 950 by the user's eye901 in this configuration. For example, the distal lens 940 may includea liquid lens that is not actuated and therefore may not add opticalpower to the user's eye 901; the user may thus be able to visualize anobject 950 in the field-of-view of the user's eye without magnificationor visual correction.

In some embodiments, the proximal lens 910 may include a variety ofcomponents and configurations. In another embodiment, the proximal lens910 may include a rigid lens. The proximal lens 910 may include aprescription lens. The proximal lens 910 may include a first surfacethat is concave, as shown, or may have another shape (e.g., convex,flat, or freeform); the surface may have a radius of curvature to atleast partially correct the vision of the user's eye 901. The proximallens 910 may include any suitable material, such as those described inconnection with FIG. 1 . Accordingly, repetitive description of likeelements employed in one or more embodiments described herein may beomitted for sake of brevity.

In some embodiments, the selective transmission interface 920 mayinclude a variety of components and configurations. In some embodiments,the selective transmission interface 920 may include a hot mirror coatedFresnel combiner element that diverts light towards the sensor 930. Insome embodiments, the selective transmission interface 920 may bereferred to as an immersed reflector herein. In another embodiment, theselective transmission interface 920 may be at least semi-rigid so as toserve as a backplane of the distal lens 940 or the proximal lens 910,either of which may be an accommodative lens (e.g., a liquid lens). Theselective transmission interface 920 may include any suitable component,such as those described in connection with FIG. 1 . Accordingly,repetitive description of like elements employed in one or moreembodiments described herein may be omitted for sake of brevity.

In some embodiments, the distal lens 940 may include a variety ofcomponents and configurations. The distal lens 940 may include anaccommodative lens. In some embodiments, the accommodative lens mayinclude a liquid lens. In one embodiment, the liquid lens may include avolume of liquid enclosed between flexible, transparent surfaces. Insome embodiments, two such surfaces, one forming the lens front surfaceand one forming the lens back surface, may be attached to one another attheft edges to form a sealed chamber containing the fluid, Both surfacesmay be flexible, or one may be flexible and one rigid. In anotherembodiment, the selective transmission interface 920 may serve as one ofthe surfaces for the lens's back surface. In one embodiment, fluid maybe introduced into or removed from the chamber to vary its volume;further, as the volume of liquid changes, so does the curvature of thesurface(s), and thus the power of the liquid lens changes as well. Inanother embodiment, by moving the periphery of an elastic surfaces, theliquid inside the liquid lens may be redistributed such that thecurvature of the lens is changed. The changed curvature of the liquidlens surface bounded by the elastic surfaces may vary the optical power(or diopter) of the liquid lens. The surface(s) may include a flexible,transparent, water impermeable material, such as clear and elasticpolyolefins, polycycloaliphatics, polyethers, polyesters, polyimides andpolyurethanes, for example, polyvinylidene chloride films, includingcommercially available films.

In another embodiment, the distal lens 940 including a liquid lens mayinclude one or more liquid filled cavities, contained by a correspondingnumber of surfaces. One or more such liquid filled cavities may besealed and may be placed under pressure to maintain the surfaces in astretched state. The surface(s) may be sealed to a periphery of theselective transmission interface 920 that may serve as a backplane forthe liquid lens. Surface(s) may be sealed to the selective transmissioninterface 920 by any known method, such as heat sealing, adhesivesealing or laser welding.

In some embodiments, the liquid in the liquid lens may includeappropriate index of refraction and viscosity suitable for use in fluidfilled lenses, such as, for example, degassed water, mineral oil,glycerin and silicone products, among others that are commonly known orused for fluid filled lenses. In some embodiments, the liquid of theliquid lens may include one or more dissolved pigments. The pigment(s)cause the liquid to absorb or reflect light in a given wavelength range.The pigment(s) may cause the liquid to be opaque, semi-opaque, orselectively absorbent in a portion of the operating spectrum of the lensassembly 905.

In some embodiments, a reservoir may be attached to a frame not shown)including at least a portion of the lens assembly 905 and may include ahollow cavity containing fluid that may be injected into or removed fromthe liquid lens. The reservoir may have a mechanism or actuator to movefluid into or out of the liquid lens. In one embodiment, the reservoirmay be made of a rigid material, and may be fitted with a piston that ismechanically coupled to an adjustment mechanism or actuator, such as athumb wheel, a barrel, a clamp or a lever.

In alternative embodiments, the distal lens 940 including the liquidlens may focus light based on an electrowetting mechanism; that is, anapplied voltage may change the curvature of the liquid lens. By applyingan external voltage to the liquid, the surface profile of the liquid maybe tuned because of a contact angle change resulting from the appliedvoltage. Consequently, the focal length of the liquid lens may bevaried.

In some embodiments, the distal lens 940 including the liquid lens mayinclude a liquid crystal material, Such liquid crystal materials mayhave properties such as index of refraction, that be altered based onelectro-optical and magneto-optical effects. In some embodiments, suchliquid crystal materials, may have at least one semi-ordered,mesomorphic phase in addition to a solid phase and an isotropic liquidphase. Well known mesomorphic phases are the smectic, nematic, andcholesteric phases, in some embodiments, the liquid lens may include aliquid crystal that changes its refractive index in response to a changeof an applied electric field strength to produce a variation of focallength in the liquid lens including a body of nematic liquid crystalmaterial. In some embodiments, the liquid lens may include a body ofliquid crystal material that may be contained between surfaces. Thesurface(s) of the liquid lens may take on any suitable shape for visioncorrection, for example, a convex or concave shape, or any of the shapesshown and described in connection with FIG. 7 , Accordingly, repetitivedescription of like elements employed in one or more embodimentsdescribed herein may be omitted for sake of brevity. More generally, thebody of the liquid lens including liquid crystal material may have anydesired shape and may be a layer of uniform thickness. Further, anelectromagnetic field that is graded in strength from the center towardsthe edge of the liquid lens body may be used to achieve a focusingeffect.

FIGS. 10A and 10B show another example optical system of an eye,eye-tracking component, and an actuatable accommodative (e.g., liquid)lens, in accordance with example embodiments of the disclosure. Theoptical system 1000 may include a variety of components andconfigurations. In particular, in a first configuration 1001, a user'seye 1002 may be position behind a structural support element 1005.Radiation (e.g., infrared light) may reflect off of an immersedreflective surface 1020 and may be diverted toward a sensor (not shown).The radiation may be used to track the eye 1002, for example, bytracking a pupil of the eye 1002, for example, as further described inconnection with FIG. 2 . Further, an adjustable lens 1030 may be coupledto the immersed reflective surface 1020. The adjustable lens 1030 may bean accommodative lens that may be actuated by an actuator (not shown).The adjustable lens 1030 may change its shape and/or morphology in orderto correct a user's vision. In another embodiment, an eye-trackingsubsystem (not shown) may be programmed to trigger a change in anoptical power of the adjustable lens 1030 that may also serve as anaccommodative lens based on the depth at which the right and left eyesare focused.

In another embodiment, the adjustable lens 1030 may be actuated (e.g.,as shown and described in connection with FIG. 9 ) in a firstoperational state, and therefore, the adjustable lens 1030 may changemorphology and become a negative lens. This may cause the apparentlocation of the object 1050 to be closer to the user's eye 1002 and mayalso have the effect of demagnifying the object 1050. In comparison, inanother configuration 1003, as shown in FIG. 10B, the adjustable lens1040 may not be actuated. Consequently, the image of the object 1060 maybe visually appear at a farther location with respect to the eye 1004 ofthe user.

As mentioned, in various embodiments, the optical system 1000 mayinclude a structural support element 1005. The structural supportelement 1005 may have a non-zero optical power. The structural supportelement 1005 may transmit light having a selected property and may nottransmit light that does not have the selected property. The selectedproperty may include a passband range of wavelengths such that thestructural support element 1005 transmits light within the passbandrange of wavelengths and such that the structural support element 1005is at least partially non-transmissive for light outside the passbandrange. The selected property may include a polarization state ofelectromagnetic radiation; further, the structural support element 1005may include a reflective polarizer (not shown) configured to transmitlight having a first polarization state and to reflect light having asecond polarization state that is different from the first polarizationstate.

The optical system 1000 may include a sensor (not shown). Further, thepassband range may include at least a portion of a visible spectrum oflight. The structural support element 1005 may be configured to reflectat least a portion of an infrared spectrum of light such that infraredlight reflected from the eye 1002 of a user is diverted toward thesensor. For example, the structural support element 1005 may include animmersed reflective surface 1020 or an optical substrate 1020 having aplurality of concentric facets that may be used to divert the portion ofthe infrared spectrum of light to the sensor. Examples of sensors thatmay be used in connection with the embodiment shown and described inconnection with FIG. 10 were previously discussed in connection withFIG. 2 and the related description. Accordingly, repetitive descriptionof like elements employed in one or more embodiments described hereinmay be omitted for sake of brevity.

The optical system 1000 may further include an adjustable lens 1030coupled to the structural support element 1005, and the structuralsupport element may include a rigid lens including a non-zero opticalpower. The adjustable lens 1030 may additionally include a deformableelement that: may be supported by the structural support element 1005such that the structural support element 1005 serves as a backplane ofthe adjustable lens 1030. When deformed, the deformable element maychange an optical property of the adjustable lens 1030, such as arefractive index of the adjustable lens 1030.

In some embodiments, the adjustable lens 1030 may include a liquid lens,and the deformable element may be sealed to the structural supportelement 1005 to hold a deformable optical medium within a cavity locatedbetween the deformable element and the structural support element 1005.Moreover, the structural support element 1005 may include a backplane ofthe liquid lens.

The optical system 1000 may be used to correct the vision of a user. Forexample, the adjustable lens 1030 may be configured to correct for atleast a portion of a refractive error of an eye 1002 of the user.Further, the structural support element 1005 and the adjustable lens1030 may be configured in a manner that reduces a chromatic aberrationcaused by the adjustable lens 1030.

The optical system 1000 may include a head-worn frame (not shown) thatmay be configured to hold the structural support element 1005 and theadjustable lens 1030 in front of an eye 1002 of a user. For example, thehead-worn frame may hold the structural support element 1005 such that aproximal surface of the structural support element 1005 faces a user anda distal surface of the structural support element 1005 includes thebackplane of the adjustable lens 1030. The head-worn display may beconfigured to transmit images through the structural support element1005 and the adjustable lens 1030 to an eye 1002 of a user.

The optical system 1000 may include an eye-tracking subsystem (notshown) programmed to use an output of the sensor to track movement ofthe eye 1002 of the user, for example, by tracking the pupil of the eye1002 of the user. The eye-tracking subsystem may be further programmedto: track a gaze direction of both a right eye of the user and a lefteye of the user. The eye-tracking subsystem may calculate, based on thegaze directions of the right and left eyes of the user, a depth at whichthe right and left eyes of the user are focused. The adjustable lens1030 may include an accommodative lens and the eye-tracking subsystemmay be programmed to trigger a change in an optical property of theadjustable lens 1030 based on the depth at which the right and left eyesare focused.

FIG. 11A shows another example optical system of an eye, eye-trackingcomponent, and actuatable accommodative (e.g., liquid) lens having acurved optical substrate, in accordance with example embodiments of thedisclosure. The optical system 1100 may include a variety of componentsand configurations. In particular, in a first configuration 1101, auser's eye 1102 may be position behind a structural support element1105. Radiation (e.g., infrared light) may reflect off of an immersedreflective surface 1120 and may be diverted toward a sensor (not shown).The radiation may be used to track the eye 1102, for example, bytracking a pupil of the eye 1102, for example, as further described inconnection with FIG. 2 . Accordingly, repetitive description of likeelements employed in one or more embodiments described herein may beomitted for sake of brevity. Further, an adjustable lens 1130 may becoupled to the structural support element 1105, for example, at a curvedsurface 1125, which may serve as a backplane for the adjustable lens1130. The curved surface 1125 may have a radius of curvature and/orother morphological properties to meet one or more prescriptionrequirements. In some embodiments, adjustable lens 1130 such as liquidlenses may be fabricated on the curved surface 1125 by suitablemanufacturing techniques. In non-limiting examples, such manufacturingtechniques may be based on are based on thin-film deposition methods,including, but not limited to, physical vapor deposition (including, forexample, evaporative deposition and ion beam assisted deposition),chemical vapor deposition, ion beam deposition, molecular beam epitaxy,and sputter deposition.

The adjustable lens 1130 may be an accommodative lens that may beactuated by an actuator (not shown). The adjustable lens 1130 may changeits shape and/or morphology in order to correct a user's vision. Inanother embodiment, an eye-tracking subsystem (not shown) may beprogrammed to trigger a change in an optical power of the adjustablelens 1130 that serves as an accommodative lens based on the depth atwhich the right and left eyes are focused. In another embodiment, theadjustable lens 1130 may be actuated from a first operational state(e.g., a non-refractive state as shown and described in connection withFIG. 9 ), and therefore, the adjustable lens 1030 may change morphologyand become a negative lens. This may cause the apparent location of theobject 1150 to be closer to the user's eye 1102 and may also have theeffect of demagnifying the object 1050. In comparison, in anotherconfiguration 1103 in FIG. 11B, the adjustable lens 1040 may not beactuated. Consequently, the image of the object 1160 may appear fartheraway with respect to the eye 1140 of the user.

FIG. 12A shows plots of the amount of magnification versus the opticalpower of an accommodative (e.g., liquid) lens, where the optical powervaries between approximately −3 diopters (D) to approximately +3 D, inaccordance with example embodiments of the disclosure. In variousembodiments, optical power (also referred to as dioptric power,refractive power, focusing power, or convergence power) may refer to thedegree to which a lens, mirror, or other optical component converges ordiverges light. Optical power may be equal to the reciprocal of thefocal length of the component. In some embodiments, converging lensesmay have positive optical power, while diverging lenses may havenegative power.

In some embodiments, depending on the range of optical power introducedby the liquid lenses, varying amounts of magnification may be expected.In particular, plot 1201 shows a plot 1208 the amount of magnification1204 of an accommodative lens versus the optical power 1206 of theaccommodative lens in units of diopters. In another embodiment, theamount of magnification 1204 may vary between 0.94 to 1.08, and theoptical power may vary between approximately −3 D to approximately +3 D.Accordingly, the accommodative lens may introduce a magnification changeranging from approximately −6% to approximately 8% (which may beimperceptible to the human eye). An accommodative lens having suchcharacteristics may be applicable for a display system, such as thosedescribed variously herein.

FIG. 12B shows plots of the amount of magnification versus the opticalpower of an accommodative (e.g., liquid) lens, where the optical powervaries between approximately 20 D to approximately 40 D, in accordancewith example embodiments of the disclosure. In particular, plot 1203shows a plot 1218 the amount of magnification 1214 of an accommodativelens versus the optical power 1216 of the accommodative lens in units ofdiopters. In another embodiment, the amount of magnification 1214 variesbetween approximately 1.5 to approximately 5, and the optical powervaries between approximately 20 D to approximately 40 D. It may bedifficult for a single liquid lens to achieve a dynamic range of thismagnitude; however, multiple liquid lenses, in combination with apassive lens could be used to cover the range of optical powersconsidered. Consequently, an optical system including such lenses may beused to change the perceived magnification from approximately 1.5 timesto approximately 5 times. Such an accommodative lens may have manyapplications, for example, in surgical loupes where the surgeon may needto zoom-in or zoom-out of an area under examination.

FIG. 13 shows an example flow-diagram for performing example operationsof the optical systems and various components described herein, inaccordance with example embodiments of the disclosure. At block 1305,light may be directed to an optical sensor by a doublet lens. In oneembodiment, the doublet lens may include a proximal lens configured totransmit light toward an eye of a user and a distal lens that isconfigured to, in combination with the proximal lens, correct for atleast a portion of a refractive error of the eye of the user. In someembodiments, the outer surfaces of the first lens and the second lens ofthe doublet lens may correspond to the surface exposed to incidentradiation and the surface from which radiation exits the doublet lens.In some examples, the outer surfaces of the first lens and second lensmay have a profile that is flat, curved, or has a shape that allows forthe correction of a user's visual refractive error.

In some embodiments, the lenses of the doublet lens may be formed fromoptically transmissive media (e.g., glass or plastic). Further, thecomponents of the doublet lens may include optically transmissive mediathat include identical or different materials. In some examples, theoptically transmissive media used to make the doublet lens may be chosento minimize the chromatic aberration of the doublet lens. Examples ofoptical media that may be used to form the lenses are further describedin connection with FIG. 1 , above.

In some embodiments, the doublet lens may include a selectivetransmission interface that couples the proximal lens to the distallens. In some embodiments, the selective transmission interfaceincluding a common surface between the proximal lens and the distal lensmay allow for absorption and/or transmission of radiation by the doubletlens over a visible portion of the spectrum and a reflection ofradiation by the doublet over the near-infrared portion of the spectrum.In one example, the selective transmission interface may include anoptical coating on the common surface between the proximal lens and thedistal lens. In another example, the selective transmission interfacemay include reflective polarizers that selectively absorption andtransmit radiation of a given polarization state while reflectingradiation of a different polarization state.

At block 1310, light may be transmitted within a passband range ofwavelengths. In another embodiment, the light may be at least partiallyblocked outside the passband range of wavelengths. In some embodiments,a selective transmission interface may be configured to transmit lighthaving a selected property within the passband range of wavelengths andto not transmit light that does not have the selected property or isoutside the passband range of wavelengths. In another example, thepassband range may include at least a portion of a visible spectrum oflight. The selected property may include a polarization state ofelectromagnetic radiation. The selective transmission interface mayinclude a reflective polarizer configured to transmit light having afirst polarization state and to reflect or absorb light having a secondpolarization state that is different than the first polarization state.

At block 1315, information may be received about light reflected off aneye of a user from an optical sensor. In some examples, the informationabout the light may be received via radiation captured by the opticalsensor. The captured radiation may be digitized, that is, converted toan electronic signal by the optical sensor. Further, a digitalrepresentation of this electronic signal may be transmitted to one ormore processors (e.g., processors associated with a device such as acomputer). In some examples, the digital representation may be processedby the one or more processors to generate an image of the eye and/or totrack the movement of the eye. In another example, the tracking of theeye movements may be performed by executing, by the one or moreprocessors, one or more algorithms represented by computer instructionsstored on non-transient memory. In some examples, at least portions ofsuch algorithms may be performed using on-chip logic, for example, usingan application-specific integrated circuit (ASIC).

At block 1325, a gaze of the user may be detected based on theinformation about the light reflected off the eye of the user. In someembodiments, detecting the gaze of the user may include tracking a gazedirection of both a right eye of the user and a left eye of the user andcalculating, based on the gaze directions of the right and left eyes ofthe user, a depth at which the right and left eyes of the user arefocused. In some embodiments, the tracking may provide information aboutthe gaze for one eye or both eyes at the same time. In another example,the determination of the user's gaze and data related to the user's agemay facilitate an estimation of an accommodative state for the eyes ofthe user.

At block 1320, a state of an optical system worn by the user may bechanged in response to detecting the gaze of the user. In someembodiments, the optical system may include an optical sensor, a doubletlens, and an adjustable lens. The doublet lens may include a proximallens and distal lens, as variously discussed in connection with thedisclosure. Further, changing the state of the optical system mayinclude modifying a focal length of a display and/or changing a focus ofthe adjustable lens. In an alternative embodiment, at least one of theproximal and distal lenses may include the adjustable lens and changingthe state of the optical system may include triggering an actuator tomodify an optical property of the adjustable lens by deforming theadjustable lens.

FIG. 14 shows another example flow-diagram for example operations of theoptical systems and components various described herein, in accordancewith example embodiments of the disclosure. At block 1405, an opticalsubstrate may be coated with a selective transmission layer. In someembodiments, the selective transmission layer may be configured totransmit light having a selected property within a passable range ofwavelengths and may be configured to not transmit light not having theselected property or is outside the passable range of wavelengths. Inanother example, the passband range may include at least a portion of avisible spectrum of light.

In one embodiment, the selective transmission layer (also referred to asselective transmission interface herein) may include a hot mirrorcoating which may reflect near-infrared radiation and may transmitand/or absorb visible light. In another embodiment, the selectivetransmission interface may include a dichroic filter that may reflectnear-infrared radiation and transmit and/or absorb visible light. Insome embodiments, the dichroic filter may include alternating layers ofoptical coatings with different refractive indices. The interfacesbetween the layers of different refractive indices may produce phasedreflections, selectively reinforcing certain wavelengths of light andinterfering with other wavelengths. By controlling the thickness andnumber of the layers, the frequency (wavelength) of the passband of thefilter may be tuned and made as wide or narrow as desired.

In a further embodiment, the selective transmission interface mayinclude a dielectric mirror (also known as a Bragg mirror) that mayreflect near-infrared radiation and transmit and/or absorb visiblelight. In some embodiments, the dielectric mirror may be composed ofmultiple thin layers of dielectric material. By modifying the type andthickness of the dielectric layers, one may design an optical coatingwith specified reflectivity at different wavelengths of light. In someembodiments, the dielectric mirror may include a stack of layers with ahigh refractive index interleaved with layers of a low refractive index.The thicknesses of the layers may be chosen such that the path-lengthdifferences for reflections from different high-index layers are integermultiples of the wavelength for which the mirror is designed.

In some embodiments, the dielectric mirrors may be based on are based onthin-film deposition methods, including, but not limited to, physicalvapor deposition (which includes evaporative deposition and ion beamassisted deposition), chemical vapor deposition, ion beam deposition,molecular beam epitaxy, and sputter deposition.

At block 1410, a proximal surface of the optical substrate may becoupled to a proximal lens configured to transmit light toward an eye ofa user. In some examples, the proximal surface of the optical substratemay be coupled to the proximal lens using an index-matching material.The index matching material may include a substance, such as a liquid,cement (adhesive), or gel, which has an index of refraction that closelyapproximates that of the proximal lens and the optical substrate. Byusing an index-matching material between the optical substrate and theproximal lens, radiation may pass from the optical substrate to theproximal lens without significant reflection nor refraction. In someexamples, polymers dissolved in volatile organic compounds (VOCs), suchas nitrocellulose, and acrylic compounds dissolved in lacquer thinnerand/or a mixture of several solvents (typically containing butyl acetateand xylene or toluene) may be used as an index-matching layer.

At block 1415, a distal surface of the optical substrate may be coupledto a distal lens. In some embodiments, the distal lens may be configuredto, in combination with the proximal lens, correct for at least aportion of a refractive error of the eye of the user. In some examples,the distal surface of the optical substrate may be coupled to the distallens using an index-matching material. The index matching material mayinclude a substance, such as a liquid, cement (adhesive), or gel, whichhas an index of refraction that closely approximates that of the distallens and the optical substrate. By using an index-matching materialbetween the optical substrate and the distal lens, radiation may passfrom the optical substrate to the distal lens without significantreflection nor refraction. In some examples, polymers dissolved involatile organic compounds (VOCs), such as nitrocellulose, and acryliccompounds dissolved in lacquer thinner and/or a mixture of severalsolvents (typically containing butyl acetate and xylene or toluene) maybe used as an index-matching layer.

At block 1420, the optical substrate, the proximal lens, and the distallens may be secured to a head-worn optical system. The head-worn opticalsystem may be configured to hold the optical substrate, the proximallens, and the distal lens in front of an eye of a user. For example, thehead-worn optical system may hold the optical substrate such that aproximal surface of the optical substrate faces a user and a distalsurface of the optical substrate includes the backplane of the distallens. The head-worn display may be configured to transmit images throughthe optical substrate, the proximal lens, and the distal lens to an eyeof a user.

As detailed above, the computing devices and systems described and/orillustrated herein broadly represent any type or form of computingdevice or system capable of executing computer-readable instructions,such as those contained within the modules described herein. In theirmost basic configuration, these computing device(s) may each include atleast one memory device and at least one physical processor.

In some examples, the term “memory device” generally refers to any typeor form of volatile or non-volatile storage device or medium capable ofstoring data and/or computer-readable instructions. In one example, amemory device may store, load, and/or maintain one or more of themodules described herein. Examples of memory devices include, withoutlimitation, Random Access Memory (RAM), Read Only Memory (ROM), flashmemory, Hard Disk Drives (HDDs), Solid-State Drives (SSDs), optical diskdrives, caches, variations or combinations of one or more of the same,or any other suitable storage memory.

In some examples, the term “physical processor” generally refers to anytype or form of hardware-implemented processing unit capable ofinterpreting and/or executing computer-readable instructions. In oneexample, a physical processor may access and/or modify one or moremodules stored in the above-described memory device. Examples ofphysical processors include, without limitation, microprocessors,microcontrollers, Central Processing Units (CPUs), Field-ProgrammableGate Arrays (FPGAs) that implement softcore processors,Application-Specific Integrated Circuits (ASICs), portions of one ormore of the same, variations or combinations of one or more of the same,or any other suitable physical processor.

Although illustrated as separate elements, the modules described and/orillustrated herein may represent portions of a single module orapplication. In addition, in certain embodiments one or more of thesemodules may represent one or more software applications or programsthat, when executed by a computing device, may cause the computingdevice to perform one or more tasks. For example, one or more of themodules described and/or illustrated herein may represent modules storedand configured to run on one or more of the computing devices or systemsdescribed and/or illustrated herein. One or more of these modules mayalso represent all or portions of one or more special-purpose computersconfigured to perform one or more tasks.

In addition, one or more of the modules described herein may transformdata, physical devices, and/or representations of physical devices fromone form to another. For example, one or more of the modules (e.g., aneye-tracking module) described herein may receive sensor datacorresponding to radiation from the eye of a user to be transformed,transform the sensor data, output a result of the transformation to oneor more processors, use the result of the transformation to performeye-tracking, and store the result of the transformation to a storagedevice. Additionally or alternatively, one or more of the modulesrecited herein may transform a processor, volatile memory, non-volatilememory, and/or any other portion of a physical computing device from oneform to another by executing on the computing device, storing data onthe computing device, and/or otherwise interacting with the computingdevice.

In some embodiments, the term “computer-readable medium” generallyrefers to any form of device, carrier, or medium capable of storing orcarrying computer-readable instructions. Examples of computer-readablemedia include, without limitation, transmission-type media, such ascarrier waves, and non-transitory-type media, such as magnetic-storagemedia (e.g., hard disk drives, tape drives, and floppy disks),optical-storage media (e.g., Compact Disks (CDs), Digital Video Disks(DVDs), and BLU-RAY disks), electronic-storage media (e.g., solid-statedrives and flash media), and other distribution systems.

Embodiments of the instant disclosure may include or be implemented inconjunction with an artificial reality system. Artificial reality is aform of reality that has been adjusted in some manner beforepresentation to a user, which may include, e.g., a virtual reality (VR),an augmented reality (AR), a mixed reality (MR), a hybrid reality, orsome combination and/or derivatives thereof. Artificial reality contentmay include completely generated content or generated content combinedwith captured (e.g., real-world) content. The artificial reality contentmay include video, audio, haptic feedback, or some combination thereof,any of which may be presented in a single channel or in multiplechannels (such as stereo video that produces a three-dimensional effectto the viewer). Additionally, in some embodiments, artificial realitymay also be associated with applications, products, accessories,services, or some combination thereof, that are used to, e.g., createcontent in an artificial reality and/or are otherwise used in (e.g.,perform activities in) an artificial reality. The artificial realitysystem that provides the artificial reality content may be implementedon various platforms, including a head-mounted display (HMD) connectedto a host computer system, a standalone HMD, a mobile device orcomputing system, or any other hardware platform capable of providingartificial reality content to one or more viewers.

The process parameters and sequence of the steps described and/orillustrated herein are given by way of example only and may be varied asdesired. For example, while the steps illustrated and/or describedherein may be shown or discussed in a particular order, these steps donot necessarily need to be performed in the order illustrated ordiscussed. The various exemplary methods described and/or illustratedherein may also omit one or more of the steps described or illustratedherein or include additional steps in addition to those disclosed.

The preceding description has been provided to enable others skilled inthe art to best utilize various examples of the exemplary embodimentsdisclosed herein. This exemplary description is not intended to beexhaustive or to be limited to any precise form disclosed. Manymodifications and variations are possible without departing from thespirit and scope of the instant disclosure. The embodiments disclosedherein should be considered in all respects illustrative and notrestrictive. Reference should be made to the appended claims and theirequivalents in determining the scope of the instant disclosure.

Unless otherwise noted, the terms “connected to” and “coupled to” (andtheir derivatives), as used in the specification and claims, are to beconstrued as permitting both direct and indirect (i.e., via otherelements or components) connection. In addition, the terms “a” or “an,”as used in the specification and claims, are to be construed as meaning“at least one of.” Finally, for ease of use, the terms “including” and“having” (and their derivatives), as used in the specification andclaims, are interchangeable with and have the same meaning as the word“comprising.”

What is claimed is:
 1. An optical system comprising: a structuralsupport element that: transmits light having a selected property; anddoes not transmit light that does not have the selected property; and anadjustable lens coupled to the structural support element, wherein theadjustable lens comprises a deformable element that: is supported by thestructural support element such that the structural support elementcomprises a backplane of the adjustable lens; and when deformed, changesan optical property of the adjustable lens.
 2. The optical system ofclaim 1, further comprising a sensor, wherein the structural supportelement is configured to reflect at least a portion of an infraredspectrum of light such that infrared light reflected from an eye of auser is diverted toward the sensor.
 3. The optical system of claim 1,further comprising a headwear frame configured to hold the structuralsupport element such that a proximal surface of the structural supportelement faces a user and a distal surface of the structural supportelement comprises the backplane of the adjustable lens.
 4. The opticalsystem of claim 1, wherein: the adjustable lens comprises a liquid lens;and the deformable element is sealed to the structural support elementto hold a deformable optical medium within a cavity located between thedeformable element and the structural support element.
 5. The opticalsystem of claim 1, wherein the structural support element comprises anon-zero optical power.
 6. The optical system of claim 1, wherein theselected property comprises a passband range of wavelengths such thatthe structural support element: transmits light within the passbandrange of wavelengths; and is at least partially non-transmissive forlight outside the passband range.
 7. The optical system of claim 6,further comprising a sensor, wherein: the passband range comprises atleast a portion of a visible spectrum of light; and the structuralsupport element is configured to reflect at least a portion of aninfrared spectrum of light such that infrared light reflected from aneye of a user is diverted toward the sensor.
 8. The optical system ofclaim 7, further comprising an eye-tracking subsystem programmed to usean output of the sensor to track movement of the eye of the user.
 9. Theoptical system of claim 8, wherein the eye-tracking subsystem isprogrammed to: track a gaze direction of both a right eye of the userand a left eye of the user; and calculate, based on the gaze directionsof the right and left eyes of the user, a depth at which the right andleft eyes of the user are focused.
 10. The optical system of claim 9,wherein: the adjustable lens comprises an accommodative lens; and theeye-tracking subsystem is programmed to trigger a change in an opticalproperty of the adjustable lens based on the depth at which the rightand left eyes are focused.
 11. The optical system of claim 1, wherein:the selected property comprises a polarization state of electromagneticradiation; and the structural support element comprises a reflectivepolarizer configured to transmit light having a first polarization stateand to reflect light having a second polarization state that isdifferent from the first polarization state.
 12. The optical system ofclaim 1, wherein: the adjustable lens comprises a liquid lens; and thestructural support element comprises a backplane of the liquid lens. 13.The optical system of claim 1, wherein the structural support elementcomprises an immersed reflective surface.
 14. The optical system ofclaim 1, wherein the structural support element comprises an opticalsubstrate having a plurality of concentric facets.
 15. The opticalsystem of claim 1, wherein the structural support element and theadjustable lens are configured in a manner that reduces a chromaticaberration caused by the adjustable lens.
 16. The optical system ofclaim 1, further comprising a head-worn display configured to transmitimages through the structural support element and the adjustable lens toan eye of a user.
 17. An optical system comprising: a rigid lenscomprising a non-zero optical power; and an adjustable lens coupled tothe rigid lens, wherein the adjustable lens comprises a deformableelement that: is supported by the rigid lens such that the rigid lenscomprises a backplane of the adjustable lens; and when deformed, changesan optical property of the adjustable lens.
 18. The optical system ofclaim 17, further comprising an actuator that, when actuated, applies aforce to the adjustable lens that causes the adjustable lens to deformin a manner that changes the optical property.
 19. The optical system ofclaim 17, further comprising a head-worn frame dimensioned to hold therigid lens and the adjustable lens in front of an eye of a user, whereinthe adjustable lens is configured to correct for at least a portion of arefractive error of the eye of the user.
 20. A method comprising:receiving, from an optical sensor, information about infrared lightreflected off an eye of a user, wherein the infrared light reflected offthe eye of the user is directed to the optical sensor by an opticalelement comprising: a structural support element that: transmits atleast a portion of light in a visible spectrum; and reflects at least aportion of light in an infrared spectrum; and an adjustable lens coupledto the structural support element, wherein the adjustable lens comprisesa deformable element that: is supported by the structural supportelement such that the structural support element comprises a backplaneof the adjustable lens; and when deformed, changes an optical propertyof the adjustable lens; detecting, based on the information about thelight reflected off the eye of the user, a gaze of the user; and inresponse to detecting the gaze of the user, changing a state of anoptical system that comprises the optical sensor and the opticalelement.